Wave guide coupling



P 1950 F. w. KOLLER- ETAL 7 2,522,279

WAVE GUIDE COUPLING Filed Dec. 3, 1946 RUBBER ATTORNFV Ew. KOLLER INVENTORS. 5

Patented Sept. 12, 1950 I 2,522,279 i H n f wava'otiins COUPLING Fredrick W. Koller, Green Village,-'N. IL, and Edmund Ley, Jamaica, N. 'Y.,-assignors toBell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application ecember a, 1946; Serial No; 'zis ssz 3 Claims. (Cl. 178-44) "This invention relates to wave guides and mor particularly to vices.

'An object of the invention is to couple misaligned wave guide parts without introducing appreciable loss and change in characteristic impedance.

"Another object of the invention is to connect wave guide parts so as to allow limited flexing movement therebetween, and at the same time to maintain the loss of the connection comparable to arigid waveguide and render the power leak; age negligible. I n

A'feature of th invention is a vertebra wave guide characterized by nested plates having aligned apertures for wave transmission therethrough, each plate having a choke groove around the aperture to prevent leakage loss of wave energy.

Another feature-of th invention is a vertebra wave guide characterized by nested plates having aligned wave transmission apertures',.said

movement. k n

Fig. -1 shows a side view of assembled wave guide coupler in accordance with the invention;

Fig. 2 is an exploded sectional view; Fig. 3 is a front view of the coupler; Fig; 4 isa perspective view of the coupler;

plates being held together for limited flexing .Figs. 5 and 6 show front views of apair of choke vertebra elements in operative positions.

The figures of the drawing, as shown, are'sub-' stantially drawn to scale.

wave guide'choke coupling de- Flexible wave guides formed of separate, spaced choke wafers or plates embedded in a rubber casing are known. Such devices are characterized by appreciable loss due to wave leakage through the casing permitted by the spacing between the choke wafers, and by more or less appreciable changes in the characteristic impedance introduced by the flexing of the guide.

In accordance with the invention, these 0bjectionable features are overcome by providing a vertebra wave guide or coupling, wherein separate choke wafers or plates are nested and held together 'by rods and 'rubber strips in such a manner as to permit limited twist and shear of the plates with respect to the principal axis of the composite guide or coupler, without appreciable change in transmission characteristics.

Referring to Fig. 1 of the drawing, a wave guide choke coupling I of limited flexibility is shown connected between two rigid wave guide sections 2, 3 to allow for a slight amount of misalignment therebetween. The rigid wave guide section 2 may be a rectangular wave guide integrally connected to an end plate 4' of-the coupler, while th wave guide -3 may be a section of-rec'tan-gular guide having a terminal connecting' disc joinedto a magnetron oscillator or other microwave component- The planeof the connecting disc should be perpendicular to the axis of wave guide 2 to insure'close contact between all adjacent plates of the coupler.

Referring to Figs. 2 and 3, the wave guide choke coupling I comprises a number of square.

metal plates 4, each having a choke groove ii, surrounding the rectangular wave transmission aperture 5.

Theplates 4 are nested into, close mechanical contact by a raised circular boss 1 fitting into a" ing pins Hi. The soft rubber strips l2 fit snugly and under tension in their corresponding slots.

v The choke't on plates 4 is a. circular groove approximately one-quarter of a wavelength deep a'ta suitable distance from the longitudinal axis of the rectangular guide 5; The thickness of the plate relative to the depth of groove is kept to a minimum consistent with desired mechanical strength whereby interplat'e discontinuities are spaced substantially a quarter wavelength apart to thereby mutually cancel undesirable reflections. 7

In operation, the coupling unit is connected between rigid wave guide sections 2, 3 between which a slight amount of misalignment prevails. The plates 4 are adapted to slide upon each other sufficiently to provide a limited relative shear and twist motion.

The amount of shear between a pair of adjacent, contacting plates 4, 4 is determined almost wholly by the relative diameters of boss I and counterbore 8, and will in practice be slightly modified by the existing twist. Similarly, the amount of twist will be determined by the relation of rod diameter l l to slot width w, and will in practice be slightly modified by the existing shear. The function of the soft rubber strip 12 is to distribute the total displacement equally between the plates of the coupler.

Fig. 5 shows two nested plates 4 in operative relation, angularly displaced with respect to the longitudinal axis and to each other.

The rods II are heldslots 9 by pins I0 having a screw-threaded upper end, while strips l2 are held in slots [3 by retain- Fig. 6 shows two such plates displaced linearly, parallel to the b side of the rectangular aperture 5. Various combinations of these exemplary displacements may be impressed on the plates 4 to give them a limited flexibility.

The amount of displacements should not be sufiicient to cause any appreciable. changein the characteristic impedance of guide. Furthermore, the close nesting of the plates 4 into each other, operates to prevent any- I appreciable loss or leakage of wave energy to the outside past the plates 4.

When the guide section 3 is in place with female members fitted on lugs 15 of the coupler end plate, the entire couplerassemblyinay be held tightly by a modified U-shaped clamp (not shown) for insuring fullcontact between the plates.

Whereas for one practical form of coupler, four vertebra plates 3 were found sufficient, it should be understood that the number may be any desired. Wave guides of considerable length may be formed by nesting together a sufiiciently,

large number of such plates. Such-wave guides will possess limited flexibility, negligible leakage and the transmission characteristics of similar rigid wave guides.

What is claimed is:

1. In a structure for coupling together two misaligned wave guides comprising two end plates respectively joined to said guides, and a vertebra wave-guide coupling between said end plates comprising a series of contacting square rigid plates connected between said end plates, consecutive vertebra plates having open-ended slots in the corners thereof, each plate being provided with an aligned rectangular wave transmission aperture, an annular choke trap Slll,

rounding each aperture for preventing Wave energy leakage, said plates being .nested and each having a raised circular boss on one face thereof and aslightly larger counterbore on its opposing face, a pair of longitudinal metal rods seated in said slots for joining said plates together at a pair of diagonal corners, and a pair of longitudinal rubber strips snugly fitting into the other pair of diagonal corner slots, whereby the total relative angular displacement between said end plates is distributed equally between the plates of the vertebra coupler.

2. A vertebra wave guide for microwaves comprising a series of square rigid plates, each havthe rectangular 4 ing an aligned rectangular wave transmission aperture, each plate having a circular groove approximately in depth and at a suitable radius from the longitudinal axis of said guide to prevent leakage of Wave energy transverse thereto, nesting means between adjacent plates comprising a raised boss on one face of each plate and a slightly larger corresponding counterbore on its opposite face, rigid pins and flexible rubber strips connecting consecutive plates together at ,diagonally opposite corners thereof, whereby relative angular and linear displacements be- 1 whereby relative angular and linear displacements between the plates may be produced without appreciable change in the characteristic impedance of said guide.

FREDRICK W. KOLLER. EDMUND LEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,338,441 Kohl Jan. 4, 1944 2,419,024 Iams Apr. '15, 194'? 2,419,613 Webber Apr. 29, 1947 OTHER. REFERENCES Introduction to Flexible Waveguides, in 0Q Magazine, The Radio Amateurs Journal; Published by Radio Magazines, Inc, 28 Renne Ave, Pittsfield, Mass. See pages 25, 26, 2'7, 59 and 60 in the November 1946 issue. 

